Feedback control

(a) connection between the 10V power supply to the power pin of the regulation resistance and after

Creel stand

this, connect the white cable of “bus & control” interface on remote controller to that power pin, and the brown one to the 10V power supply. [See Figure 21]

Figure 21

 Note: when connected with the regulation resistance of the inverter, analog output cable should be as short as possible and the shielding braid must be connected with shielding cables of the inverter.

8.3.3 Testing and manufacture

8.3.3.1  Power on measurement instrument and remote controller and check parameters: average time=50, voltage polarity=0, control mode=0, P=15、_I=14、_D=0.

8.3.3.2  Place a wire on the measurement instrument and set reference diameter, 1mm less than measured value. Power on traction machine controller and set traction speed to 0. Press to enter control mode. If within 20 seconds, the traction machine is not working, which means a wrong connection (see Section 8.3.2 for details), just exchange positive pin and negative pin of the analog output cable or set polarity to 1.

Because the feedback control can’t work with wrong connection, so user should follow the instructions in Section 8.3.3.1 and Section 8.3.3.2 to ensure right connection.

8.3.3.3  While starting to manufacture, first of all, power on measurement instrument and remote controller, not enter automatic control status. Set reference diameter according to technical demand.

If the measurement instrument is installed behind flume, the reference diameter can be set as real diameter. If the measurement instrument is installed in front of flume (displaying heated value), the reference value can be set a little bit higher.

8.3.3.4 Manually adjust extruding and traction speed to make the measured data close to reference diameter and after a while, when measurement data is stable (there is inertia of extruding and traction speed), press “ ” for automatic control. Under normal working circumstance, traction speed is about 1200r/m, should not be too high otherwise there is no adjusting scale of the remote controller. If the traction speed is too low while working, just manually set it at about 1200r/m. After completing manufacture, press “ ” to stop automatic control and then  power off extruder and traction machine.

8.3.3.5  The P and I parameters of remote controller decide the stability of control. The defaulted  parameters could work well under most situations. When the control is too slow or non-stable with

defaulted parameters, user should adjust these parameters:

a. When there is deviation between measured diameter and reference (positive or negative) lasting for a long time [see Figure 22(a)], it suggests that the system has “steady-state error”. Increase  parameter I to remove “steady-state error”.

b. When measured diameter is changing constantly up and down near reference for a long time [see Figure 22 (b)], it suggests that system has “vibration”. Reduce parameter I to control

“vibration”.

c. When measured diameter rapidly reaches reference and vibrates in control mode [see Figure 22(c)], it suggests that system is “overshoot”. Reduce parameter P to eliminate it.

d. When measured diameter costs long time to reach reference or could not reach in control mode [see Figure 22(d)], it suggests that system is “undershoot”. Increase parameter P to eliminate it In a word, parameter P decides adjusting speed, parameter I decides control precision. The ideal control curve is indicated by Figure 22(e).

The parameter must be saved after adjustment in case of loss when powering on next time.

(a)

(b)

(c)

(d)

(e) Figure 22

Note: “ ” denotes reference diameter

“ ” denotes measured diameter

Vibrating

Overshoot

Undershoot

Ideal control curve Steady-state error (high)

Reference Value

Measured Value Measured Value

Reference Value Steady-state error (low)

9 Communication

The remote controller or peripheral device uses RS485 to communicate with the gauge, and  peripheral devices use RS232/RS485 to communicate with remote controller. The protocols for both serial communications are the same, except some parameters are special for remote controller. Table 2 shows parameters for transmission and indicates those only for remote controller. See section 4.1 and 5.1 for detail of parameters’ range.

When remote controller or peripheral device communicates with the gauge, the former is sender and the latter is receiver. When peripheral device communicates with remote controller, the former is sender and the latter is receiver. That means remote controller is a sender and a receiver in the same time when it is connected with peripheral device and the gauge.

Data format: 1 star bit, 8 data bits and 1 stop bit, no parity checkout.

Transmission format of the sender when reading parameters:

g a u g e a d d re ss p a ra me t e r

Transmission format of acknowledge of the receiver:

g a u g e a d d re ss p a ra me t e r 2 -b yt e d a t a （ 90/100AL are 3

bytes,f r o m h i g h t o l o w ) C R C c h e c k s u m

Transmission format of the sender when writing parameters:

g a u g e a d d re ss p a ra me t e r 2 -b yt e d a t a（ 90/100AL are 3

bytes,f r o m h i g h t o l o w ) C R C c h e c k s u m

There is no acknowledge from the receiver when the sender writing parameters.

CRC check sum is the CRC sum (1-byte) of all bytes before it. CRC checking uses 8 digits CCITT cyclic redundancy check (CRC-CCITT) and its generator polynomial is: G(x)=X⁸＋_X⁵＋_X⁴＋_1.

The negative data is denoted in complement form.

 Example 1: reading diameter.

Suppose the address of the receiver is 1 (01H), and current diameter is 6.234(185AH), then the sender sends:

01H 41H

And the acknowledge of the receiver is:

01H 41H 18H 5AH CRC-check-sum

 Example 2: reading offset

Suppose the address of the gauge is 1(01H), and current offset is -5 then the sender sends:

01H 44H

And the acknowledge of the receiver is:

01H 44H FFH FBH CRC-check-sum

Suppose the address of laser diameter measurement instrument is 1(01H), and the sender is going to change reference diameter to 60.00(1770H) then it sends:

01H 66H 17H 70H CRC-check-sum

And there is no acknowledge from the receiver.

 Example 4：reading the diameter value of 100A

Suppose the address of laser diameter measurement instrument is 1（_01H），The value of current diameter is 106.350(19f6eH)，_{well then}：

Input：

01H 41H

The laser diameter measurement instrument output：

01H 41H 01H 9FH 6EH CRC-check-sum

For reading and writing other parameters, please follow the examples.

Read  Note: Theitalic parameters are only for remote controller.

 Note[1]: It is the alarm option when communicating with the gauge and the over-deviation alarm output option when communicating with remote controller.

 Note[2]: The A u t o m a t i c C o n t r o l parameter is the same as the automatic control key in the panel of remote controller, 1 for starting auto control, 0 for exit.

Additional parameters for Opmac 5AL:

Rea d p a r a m e t e r   W r i t e p a r a m e t e r  

Opmac  series instruments with Version 3.02 or above can communicate with peripheral devices via Modbus(RTU mode). Users can select this protocol in the parameter menu, see section 4.1 for detail. Read parmeters in table 2 are the register address in Modbus.

 Example 5: reading diameter value via Modbus

Suppose the address of laser diameter measurement instrument is 1（_01H），The value of current diameter is 6.234(185aH)，_{well then}：

Input：

01H 03H 00H 41H 00H 01H D4H 1EH

The laser diameter measurement instrument output：

01H 03H 02H 18H 5aH 32H 7FH

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